Disclaimer

  • References: Nigeria Centre for Disease control (NCDC), see here:

Nigeria Center for Disease Control and Prevention

Nigeria Center for Disease Control and Prevention
  • More information: for a dynamic report of the 🇳🇬 Lassa fever situation in Nigeria , go to 🔗

Lassa fever in Nigeria - data from 2020 to 2024

The overall burden of Lassa fever in Nigeria

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

The effect of seasonality on the Lassa fever incidence

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

  • Lassa fever cases in Nigeria by week show a seasonal effect: the number of cases peaks during the dry season period (from epi week 47 - week 12).
  • The seasonal increase of cases during the dry period may be attributed to an increase of the infected rodent population and/or a seasonal behavioural change in the human population resulting in a higher risk of exposure to infected animals and/or to food/household items contaminated with rodent excreta.

Lassa fever in Nigeria: where do efforts need to focus?

From January 2018 to December 2024, 75% of Lassa fever confirmed cases were from Ondo (33%), Edo (31%) and Bauchi (11%).

  • Total suspected cases: 38,754
  • Total confirmed cases: 5,879
  • Deaths from Confirmed Cases: 1,076
  • Case Fatality Ratio: 20%
  • Number of Health Care Workers: 229

Lassa fever suspected cases, confirmed cases and CFR by State, Nigeria 2020-2024

Lassa fever by State, Nigeria 2020-2024: Interactive maps

Suspected cases of Lassa fever

  • From 2017-2024, a total of 36,022 suspected cases were reported from 26 in Zamfara to 13,950 in Edo.

Case fatality rate (CFR) among confirmed Lassa fever cases

  • From 2017-2024, CFR among all lab confirmed cases in Nigeria was between 16-27% and decreased over time.
  • In 2024, overall CFR for Nigeria was 16% and differed greatly by individual State.
  • The variation in CFR is likely due to late patient presentation and differences in case management, highlighting the need for improvement.

Lassa fever infections among healthcare workers

  • From 2020-2024, a total of 212 healthcare workers (HCW) were reported among confirmed cases, that is 4% of Lassa fever cases.
  • From 2020-2024, 60% of all HCW infections were from Ondo (26%), Bauchi (20%), Edo (15%) States where 75% of all Lassa fever patients were being cared for. 12% of HCW infections are reported from Ebonyi where 6% of Lassa fever patients were being cared for.
  • Higher proportion of HCW in States with low incidence (10-30%).

Lassa fever in 2025 - Data from epi-week 1 to epi-week 9

Suspected cases of Lassa fever in 2025

  • In 2025, a total of 2,732 suspected cases were reported from 1 in Niger, Akwa Ibom, Jigawa, Yobe to 866 in Edo.

Cumulative number of confirmed Lassa fever cases in 2025

  • Nigeria has the highest burden of Lassa fever cases in West Africa.
  • Strengthening of capacity for lab diagnostics and case management in previous years resulted in greater case detection.
  • Major LF outbreaks reported in since 2018, with 5344 confirmed cases since 2020.

Seasonality of Lassa fever

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 30% decrease in the cumulative number of suspected cases reported.

  • In 2025, similar trend as per previous years confirming a seasonal effect on Lassa fever incidence.
  • Compared to 2024, 22% decrease in the cumulative number of confirmed cases reported.

States reporting Lassa fever confirmed cases in 2025

  • In 2025, as of epi week 9, 88% of LF cases are from Ondo (31%), Bauchi (24%), Edo (17%), and Taraba (16%) States.

  • Total confirmed cases: 535

  • Deaths from Confirmed Cases: 100

  • Case Fatality Ratio: 19%

  • Number of Health Care Workers: 17

Lassa fever suspected cases, confirmed cases and CFR by State in 2025

Lassa fever by State, Nigeria 2025: Interactive maps

Case fatality ratio among confirmed Lassa fever cases by State in 2025

  • As of epi week 9 2025, cumulatively 535 cases and 100 deaths (CFR=19%) across 13 States have been reported.
  • At same period 2024, a total of 27 States reported at least one confirmed cases.
  • There is a 30% decrease in the number of suspected cases reported in 2025 compared to 2024.
  • In 2024, 34 States had reported at least one suspected case versus 31 States in 2025 to date.

Health care worker infections 2020-2025 epiweek 9


  • Top 5 states:
    • 8 HCW infections in Ondo
    • 4 HCW infections in Bauchi
    • 2 HCW infections in Taraba
    • 2 HCW infections in Gombe
    • 1 HCW infections in Edo.

  • As of epi week 9 of 2025, there has been 17 healthcare workers infected, that is 3% of confirmed cases.

Lassa fever in most affected States - Data from 2020 to 2025 (as of epi-week 9)

Lassa fever in Ondo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ondo as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 743 168 21 12.50%
2024 777 154 11 7.14%
2023 849 221 22 9.95%
2022 509 180 33 18.33%
2021 183 38 9 23.68%
2020 276 246 34 13.82%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ondo State reported 168 confirmed cases including 21 deaths (CFR 12%).
  • Compared to same period 2024, this represents:
    • 4% decrease in the number of suspected cases.
    • 9% increase in the number of confirmed cases.
    • 75% increase in CFR.




  • In 2024 as of week 9:
    • 777 in the number of suspected cases.
    • 154 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 7% average CFR.




  • In 2023 as of week 9:
    • 849 in the number of suspected cases.
    • 221 in the number of confirmed cases.
    • 22 in the number of deaths.
    • 10% average CFR.




  • In 2022 as of week 9:
    • 509 in the number of suspected cases.
    • 180 in the number of confirmed cases.
    • 33 in the number of deaths.
    • 18% average CFR.




  • In 2021 as of week 9:
    • 183 in the number of suspected cases.
    • 38 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 24% average CFR.




  • In 2020 as of week 9:
    • 276 in the number of suspected cases.
    • 246 in the number of confirmed cases.
    • 34 in the number of deaths.
    • 14% average CFR.

Lassa fever in Bauchi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Bauchi as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 524 128 10 7.81%
2024 438 103 24 23.30%
2023 471 65 8 12.31%
2022 527 94 10 10.64%
2021 25 5 2 40.00%
2020 136 33 9 27.27%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Bauchi State reported 128 confirmed cases including 10 deaths (CFR 8%).
  • Compared to same period 2024, this represents:
    • 20% increase in the number of suspected cases.
    • 24% increase in the number of confirmed cases.
    • 66% decrease in CFR.




  • In 2024 as of week 9:
    • 438 in the number of suspected cases.
    • 103 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 23% average CFR.




  • In 2023 as of week 9:
    • 471 in the number of suspected cases.
    • 65 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 12% average CFR.




  • In 2022 as of week 9:
    • 527 in the number of suspected cases.
    • 94 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 11% average CFR.




  • In 2021 as of week 9:
    • 25 in the number of suspected cases.
    • 5 in the number of confirmed cases.
    • 2 in the number of deaths.
    • 40% average CFR.




  • In 2020 as of week 9:
    • 136 in the number of suspected cases.
    • 33 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 27% average CFR.

Lassa fever in Edo State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Edo as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 866 93 15 16.13%
2024 952 164 21 12.80%
2023 1099 196 24 12.24%
2022 808 143 20 13.99%
2021 661 73 11 15.07%
2020 628 263 28 10.65%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Edo State reported 93 confirmed cases including 15 deaths (CFR 16%).
  • Compared to same period 2024, this represents:
    • 9% decrease in the number of suspected cases.
    • 43% decrease in the number of confirmed cases.
    • 26% increase in CFR.




  • In 2024 as of week 9:
    • 952 in the number of suspected cases.
    • 164 in the number of confirmed cases.
    • 21 in the number of deaths.
    • 13% average CFR.




  • In 2023 as of week 9:
    • 1099 in the number of suspected cases.
    • 196 in the number of confirmed cases.
    • 24 in the number of deaths.
    • 12% average CFR.




  • In 2022 as of week 9:
    • 808 in the number of suspected cases.
    • 143 in the number of confirmed cases.
    • 20 in the number of deaths.
    • 14% average CFR.




  • In 2021 as of week 9:
    • 661 in the number of suspected cases.
    • 73 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 15% average CFR.




  • In 2020 as of week 9:
    • 628 in the number of suspected cases.
    • 263 in the number of confirmed cases.
    • 28 in the number of deaths.
    • 11% average CFR.

Lassa fever in Taraba State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Taraba as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 200 83 26 31.33%
2024 125 75 17 22.67%
2023 184 65 23 35.38%
2022 49 22 9 40.91%
2021 43 16 9 56.25%
2020 54 42 17 40.48%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Taraba State reported 83 confirmed cases including 26 deaths (CFR 31%).
  • Compared to same period 2024, this represents:
    • 60% increase in the number of suspected cases.
    • 11% increase in the number of confirmed cases.
    • 38% increase in CFR.




  • In 2024 as of week 9:
    • 125 in the number of suspected cases.
    • 75 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 23% average CFR.




  • In 2023 as of week 9:
    • 184 in the number of suspected cases.
    • 65 in the number of confirmed cases.
    • 23 in the number of deaths.
    • 35% average CFR.




  • In 2022 as of week 9:
    • 49 in the number of suspected cases.
    • 22 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 41% average CFR.




  • In 2021 as of week 9:
    • 43 in the number of suspected cases.
    • 16 in the number of confirmed cases.
    • 9 in the number of deaths.
    • 56% average CFR.




  • In 2020 as of week 9:
    • 54 in the number of suspected cases.
    • 42 in the number of confirmed cases.
    • 17 in the number of deaths.
    • 40% average CFR.

Lassa fever in Ebonyi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Ebonyi as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 72 17 8 47.06%
2024 149 38 19 50.00%
2023 116 37 19 51.35%
2022 141 29 10 34.48%
2021 57 11 3 27.27%
2020 93 55 11 20.00%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Ebonyi State reported 17 confirmed cases including 8 deaths (CFR 47%).
  • Compared to same period 2024, this represents:
    • 52% decrease in the number of suspected cases.
    • 55% decrease in the number of confirmed cases.
    • 6% decrease in CFR.




  • In 2024 as of week 9:
    • 149 in the number of suspected cases.
    • 38 in the number of confirmed cases.
    • 19 in the number of deaths.
    • 50% average CFR.




  • In 2023 as of week 9:
    • 116 in the number of suspected cases.
    • 37 in the number of confirmed cases.
    • 19 in the number of deaths.
    • 51% average CFR.




  • In 2022 as of week 9:
    • 141 in the number of suspected cases.
    • 29 in the number of confirmed cases.
    • 10 in the number of deaths.
    • 34% average CFR.




  • In 2021 as of week 9:
    • 57 in the number of suspected cases.
    • 11 in the number of confirmed cases.
    • 3 in the number of deaths.
    • 27% average CFR.




  • In 2020 as of week 9:
    • 93 in the number of suspected cases.
    • 55 in the number of confirmed cases.
    • 11 in the number of deaths.
    • 20% average CFR.

Lassa fever in Kogi State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Kogi as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 59 14 4 28.57%
2024 84 27 1 3.70%
2023 25 9 1 11.11%
2022 46 23 6 26.09%
2021 3 0 0 –
2020 53 27 8 29.63%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Kogi State reported 14 confirmed cases including 4 deaths (CFR 29%).
  • Compared to same period 2024, this represents:
    • 30% decrease in the number of suspected cases.
    • 48% decrease in the number of confirmed cases.
    • 671% increase in CFR.




  • In 2024 as of week 9:
    • 84 in the number of suspected cases.
    • 27 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 4% average CFR.




  • In 2023 as of week 9:
    • 25 in the number of suspected cases.
    • 9 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 11% average CFR.




  • In 2022 as of week 9:
    • 46 in the number of suspected cases.
    • 23 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 26% average CFR.




  • In 2021 as of week 9:
    • 3 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 9:
    • 53 in the number of suspected cases.
    • 27 in the number of confirmed cases.
    • 8 in the number of deaths.
    • 30% average CFR.

Lassa fever in Gombe State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 42 11 6 54.55%
2024 20 3 1 33.33%
2023 23 6 0 0.00%
2022 75 12 6 50.00%
2021 2 0 0 –
2020 14 5 1 20.00%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 11 confirmed cases including 6 deaths (CFR 55%).
  • Compared to same period 2024, this represents:
    • 110% increase in the number of suspected cases.
    • 267% increase in the number of confirmed cases.
    • 64% increase in CFR.




  • In 2024 as of week 9:
    • 20 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 9:
    • 23 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 9:
    • 75 in the number of suspected cases.
    • 12 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 50% average CFR.




  • In 2021 as of week 9:
    • 2 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 9:
    • 14 in the number of suspected cases.
    • 5 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 20% average CFR.

Lassa fever in Benue State, 2020-2025

  • Below is an overview of Lassa fever suspected cases, confirmed cases, deaths and average CFR in Gombe as of week 9:
Years Suspected cases Confirmed cases Deaths CFR
2025 42 11 6 54.55%
2024 20 3 1 33.33%
2023 23 6 0 0.00%
2022 75 12 6 50.00%
2021 2 0 0 –
2020 14 5 1 20.00%

Source: NCDC
  • See other tabs for yearly data




  • In 2025 only, Gombe State reported 11 confirmed cases including 6 deaths (CFR 55%).
  • Compared to same period 2024, this represents:
    • 110% increase in the number of suspected cases.
    • 267% increase in the number of confirmed cases.
    • 64% increase in CFR.




  • In 2024 as of week 9:
    • 20 in the number of suspected cases.
    • 3 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 33% average CFR.




  • In 2023 as of week 9:
    • 23 in the number of suspected cases.
    • 6 in the number of confirmed cases.
    • 0 in the number of deaths.
    • 0% average CFR.




  • In 2022 as of week 9:
    • 75 in the number of suspected cases.
    • 12 in the number of confirmed cases.
    • 6 in the number of deaths.
    • 50% average CFR.




  • In 2021 as of week 9:
    • 2 in the number of suspected cases.
    • 0 in the number of confirmed cases.
    • 0 in the number of deaths.
    • NA average CFR.




  • In 2020 as of week 9:
    • 14 in the number of suspected cases.
    • 5 in the number of confirmed cases.
    • 1 in the number of deaths.
    • 20% average CFR.

Thank you

Any questions or suggestions? Contact us: Anaïs Legand and Antoine Chaillon